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Nowhere Girl

@Kalshann They were meticulous! Like, obviously mistakes happen even at NASA, but it is one of the few places that still tries to get it right the first time because there is no margin for error once a probe is launched.

7 comments
David J. Atkinson #🟦

@gwynnion @Kalshann Yes. I worked at NASA/JPL for 20 years. We ground out every flaw we could find, but we always knew we couldn’t anticipate everything. The role of on-board fault management is to “Fail operational” if possible, but always “fail safe.” In the most minimal case, keep the antenna pointed at Earth and listen.

Nowhere Girl

@meltedcheese @Kalshann Right, exactly, because if you lose antenna orientation the mission is dead no matter what.

David J. Atkinson #🟦

@Kalshann @gwynnion …maybe. There have been difficult situations where all seemed lost and somebody said, “let’s try this.” For example, maybe another spacecraft could communicate with the one having a problem and act as a relay.

gnarf

@gwynnion @meltedcheese @Kalshann I visited a major ground station in Europe once where they managed to rescue a satellite that had a software error in the attitude control system and was tumbling uncontrolled.

They used their 32m dish and continuously sent out the software patch for about a week on highest power until it locked in by chance.

Also got some first-hand reports on how they rescued XMM-Newton in 2008 after the RF antenna switch failed. Really fascinating stuff.

Roger Moore

@gwynnion @Kalshann
That's also why they built a spare and kept it on the ground. That way they can test everything in an environment where they get a second chance if the fix doesn't work.

Axel Gutmann

@VATVSLPR @gwynnion @Kalshann Last I read they didn't have that for Voyager.

Habrok

@VATVSLPR @gwynnion @Kalshann Keeping an engineering model on the ground is done for newer missions, but for Voyager and older probes, there are no engineering models left on earth. In this case, they only have the documentation on paper and whatever people remember from previous work on the Voyager probes.

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